From 6cafb12dc85a5bdc722791cc5070968413264909 Mon Sep 17 00:00:00 2001 From: Mark McLoughlin Date: Sat, 24 Oct 2009 14:14:31 +0200 Subject: block: silently error unsupported empty barriers too With 2.6.32-rc5 in a KVM guest using dm and virtio_blk, we see the following errors: end_request: I/O error, dev vda, sector 0 end_request: I/O error, dev vda, sector 0 The errors go away if dm stops submitting empty barriers, by reverting: commit 52b1fd5a27c625c78373e024bf570af3c9d44a79 Author: Mikulas Patocka dm: send empty barriers to targets in dm_flush We should silently error all barriers, even empty barriers, on devices like virtio_blk which don't support them. See also: https://bugzilla.redhat.com/514901 Signed-off-by: Mark McLoughlin Signed-off-by: Mike Snitzer Acked-by: Alasdair G Kergon Acked-by: Mikulas Patocka Cc: Rusty Russell Cc: Neil Brown Cc: Christoph Hellwig Signed-off-by: Jens Axboe diff --git a/block/blk-core.c b/block/blk-core.c index ac0fa10..71da511 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1161,7 +1161,7 @@ static int __make_request(struct request_queue *q, struct bio *bio) const unsigned int ff = bio->bi_rw & REQ_FAILFAST_MASK; int rw_flags; - if (bio_rw_flagged(bio, BIO_RW_BARRIER) && bio_has_data(bio) && + if (bio_rw_flagged(bio, BIO_RW_BARRIER) && (q->next_ordered == QUEUE_ORDERED_NONE)) { bio_endio(bio, -EOPNOTSUPP); return 0; -- cgit v0.10.2 From 960cc0f4fef607baabc2232fbd7cce5368a9dcfd Mon Sep 17 00:00:00 2001 From: Neil Brown Date: Mon, 26 Oct 2009 08:59:17 +0100 Subject: block: use after free bug in __blkdev_get commit 0762b8bde9729f10f8e6249809660ff2ec3ad735 (from 14 months ago) introduced a use-after-free bug which has just recently started manifesting in my md testing. I tried git bisect to find out what caused the bug to start manifesting, and it could have been the recent change to blk_unregister_queue (48c0d4d4c04) but the results were inconclusive. This patch certainly fixes my symptoms and looks correct as the two calls are now in the same order as elsewhere in that function. Signed-off-by: NeilBrown Acked-by: Tejun Heo Signed-off-by: Jens Axboe diff --git a/fs/block_dev.c b/fs/block_dev.c index 9cf4b92..8bed055 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1248,8 +1248,8 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9); } } else { - put_disk(disk); module_put(disk->fops->owner); + put_disk(disk); disk = NULL; if (bdev->bd_contains == bdev) { if (bdev->bd_disk->fops->open) { -- cgit v0.10.2 From 592b09a42fc3ae6737a0f3ecf4fee42ecd0296f8 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 29 Oct 2009 11:46:12 +0100 Subject: backing-dev: ensure that a removed bdi no longer has super_block referencing it When the bdi is being removed, we have to ensure that no super_blocks currently have that cached in sb->s_bdi. Normally this is ensured by the sb having a longer life span than the bdi, but if the device is suddenly yanked, we have to kill this reference. sb->s_bdi is pointed to freed memory at that point. This fixes a problem with sync(1) hanging when a USB stick is pulled without cleanly umounting it first. Reported-by: Pavel Machek Signed-off-by: Jens Axboe diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 5a37e20..1065b71 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -610,6 +610,21 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi) kthread_stop(wb->task); } +/* + * This bdi is going away now, make sure that no super_blocks point to it + */ +static void bdi_prune_sb(struct backing_dev_info *bdi) +{ + struct super_block *sb; + + spin_lock(&sb_lock); + list_for_each_entry(sb, &super_blocks, s_list) { + if (sb->s_bdi == bdi) + sb->s_bdi = NULL; + } + spin_unlock(&sb_lock); +} + void bdi_unregister(struct backing_dev_info *bdi) { if (bdi->dev) { @@ -682,6 +697,7 @@ void bdi_destroy(struct backing_dev_info *bdi) spin_unlock(&inode_lock); } + bdi_prune_sb(bdi); bdi_unregister(bdi); for (i = 0; i < NR_BDI_STAT_ITEMS; i++) -- cgit v0.10.2